Vertical shock absorber systems for supporting a missile within a launch tube are required to have an axial and radial spring rate, or stiffness, determined by the shock migration requirements imposed on the launcher. Frequently, the shock requirements dictate a relatively soft system, that is, one in which there is some freedom of movement in axial, radial, and tilt directions. At the same time, the support system must maintain rather precise rotational alignment of the missile within the tube, thus requiring substantial stiffness in the direction of rotation about the tube center line.
Mounting systems of pre-loaded liquid springs can provide the desired spring and stiffness characteristics. In missile support systems that include a shock isolator comprised of elastomer pads or rings, as has been used and proposed before, it is a difficult problem to satisfactorily arrange hydraulic support elements and, although they provide some benefit, they do not readily provide the degree of relation between axial flexing and rotational stiffness as is desired. The required rotational stiffness is known to be achievable by a system of linkage arms and spherical bearings. This, however, adds considerable complexity to the system and requires more space within the diameter inside of an elastomer ring shock absorber.
In accordance with the present invention, hydraulic springs and systems including linkage arms and spherical bearings are unnecessary, and simplicity and effectiveness of performance are achieved. Briefly, the invention achieves these purposes by using a metal bellows attached mechanically in parallel with an elastomer shock isolator system to provide the rotational stiffness required. The bellows can be sized readily to have a low spring rate relative to the shock isolator system in the axial and lateral directions, but is relatively stiff in rotation about the axial center line. The different requirements of spring rate are met by using the elastomer shock absorber and the metal bellows in conjunction with each other rather than relying on either element alone. The metal bellows has relatively little shock dampening qualities in axial, radial and tilt directions, but these are functions that can be readily taken care of by known types of elastomer shock absorbers.
In calculated results, it has been shown that as compared with a system of like character using an elastomer shock isolator but without a metal bellows, that the metal bellows increases the system's rotational stiffness by a factor of about 15, but only increases the axial stiffness by about 8 percent.
While the invention is presently intended for application to missile mounting systems, it will be apparent that its utility is not so limited and that the sprung mass may be other than a missile, in accordance with the broader aspects of the present invention.